PERITONEAL WASHING CYTOLOGY EVALUATION IN GASTRIC CANCER STAGING AND PROGNOSTIC SIGNIFICANCE

• Grant number: 23/05043-1
• Support Opportunities: Regular Research Grants
• Start date: February 01, 2024
• End date: January 31, 2026
• Field of knowledge: Health Sciences - Medicine - Surgery
• Principal Investigator: Ulysses Ribeiro Júnior
• Grantee: Ulysses Ribeiro Júnior
• Host Institution: Instituto do Câncer do Estado de São Paulo Octavio Frias de Oliveira (ICESP). Coordenadoria de Serviços de Saúde (CSS). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil
• Associated researchers: André Roncon Dias ; Daniel José Szor ; Fátima Solange Pasini ; Márcia Saldanha Kubrusly ; Marcus Fernando Kodama Pertille Ramos ; Marina Alessandra Pereira

Abstract

Gastric cancer (GC) remains an important cause of mortality. The peritoneum is the main site of involvement in the diagnosis of advanced disease, and also the most frequent pattern of recurrence after surgery with curative intent. The evaluation of the peritoneal washing (PW) is important to determine the conduct and survival of patients. However, the sensitivity of conventional cytological tests in detecting tumor cells in the PW is limited, where many patients, even with negative cytology, have peritoneal recurrence. Furthermore, conventional cytology is positive in only 59% of patients with macroscopic peritoneal disease, and has much lower sensitivity in those without any macroscopic peritoneal metastasis after curative surgery. Since the accuracy of the cytological diagnosis leaves room for improvement, the search for techniques that can improve the evaluation is important to guarantee the real stage in patients with advanced disease. As an alternative, methodologies such as liquid cytology (LBC) were developed with the aim of seeking greater sensitivity when compared to the conventional method. In addition to enabling a monolayer slide, the technique can reduce false-negative rates, as it allows the concentration of all material for evaluation. Especially in patients with advanced GC, the technique could refine the cytological evaluation at the time of diagnostic laparoscopy to complement the stage, helping to define the ideal therapeutic approach. In addition, highly sensitive molecular diagnostics such as reverse transcription polymerase chain reaction (RT-PCR) may also provide additional information; and, more recently, the study of extracellular vesicles (EV) has been related to the prediction of the premetastatic phenotype in GC. Therefore, the present study aims to investigate the presence of tumor cells in PW obtained from patients with GC through cytopathological and molecular techniques, and isolation of VEs, and compare the results with conventional diagnosis and survival outcomes. In addition, markers of peritoneal dissemination and VEs in peripheral blood will also be evaluated. The results will be correlated with other clinicopathological parameters and patient prognosis. (AU)